Biological, activated sludge wastewater treatment process usually operates as a secondary treatment system or a tertiary treatment system for removal of suspended solids, BOD, nitrogen and/or phosphorus.
The treatment systems involve wastewater aeration, sludge recirculation and disposal waste) and aerated wastewater recirculation. The aeration system can be continuous or cyclic. The aeration system usually requires air blowers and air diffusers located in aeration tanks or proprietary air aspirators with a pump which pumps wastewater and air in an aeration chamber.
Simple one-pump aeration system usually operates as a secondary treatment process with a sludge recirculation or extended aeration secondary treatment process without a sludge recirculation. These processes do not provide a tertiary treatment and the secondary treatment which they provide is not well controlled and efficient. These systems usually require large tanks to provide adequate secondary treatment due to a lack of an adequate treatment process and controls in regard to sludge recirculation and disposal of excess sludge, and aeration and mixing in the aeration chamber, and recirculation of aerated wastewater.
Also, the aeration systems used are not efficient in regard to the oxygen transfer to the wastewater.
This invention is based on wastewater aeration by means of a pump and an air aspirator-mixer. The pump also recirculates and wastes the activated sludge produced by the biological treatment process, to maintain an activated sludge treatment process and recirculates the aerated wastewater to accomplish a tertiary treatment process. The air aspirator-mixer supplies air and causes an oxygen transfer to the wastewater by a turbulent hydraulic mixing of wastewater and air.
The objectives of this invention include the following:                to provide wastewater aeration, activated sludge recirculation and waste, and wastewater recirculation by means of the same pump,        to supply air to the wastewater and to the activated sludge and to mix the air and the wastewater and the activated sludge, and to accomplish oxygen transfer to the wastewater and to the activated sludge by an air aspirator-mixer.        to provide a tertiary biological wastewater treatment process for removal of suspended solids, BOD, nitrogen and phosphorus and which can also be used as a secondary biological wastewater treatment process for removal of suspended solids and BOD,        to provide flexibility and control of the time and rates of the wastewater and sludge aeration, sludge recirculation and waste, and the aerated wastewater recirculation, to accomplish a secondary or a tertiary wastewater treatment,        to provide wastewater treatment system which can be used for small, shop fabricated treatment plants for installation above or under ground, and large, site assembled treatment plants,        to provide wastewater treatment system which is compact and has a small foot print, and        to provide a system of low operation and maintenance requirements.        